Removes fetching of main branch (#9826)

Removes fetching of main branch, broke on Circle CI `main` branch builds

Not needed unless non-main branch default!

Author: benjaoming

.circleci/config.yml

@@ -41,8 +41,6 @@ jobs:
       - checkout
       - run: git submodule sync
       - run: git submodule update --init
-      - run: git fetch origin main  # needed for comparisson in pre-commit
-      - run: git branch -f --track main origin/main  # needed for comparisson in pre-commit
       - run: pip install --user 'tox<5'
       - run: tox -e pre-commit
       - run: tox -e migrations